METHODS: Two groups of NexGen® stemmed tibial implants (size 4) were studied: Option implants (N = 12) and PMMA Precoat implants (N = 12). Each implant design was divided into two subgroups, (N = 6), with one subgroup featuring bone marrow fat at the implant-cement interface and the other without contamination. In a mechanical testing machine, the implants underwent uniaxial loading for 20,000 cycles, while recording vertical micromotion and migration of the tibial baseplates. Subsequently, a push-out test assessed fixation strength at the cement interfaces. Results were compared using non-parametric statistics and presented as median and min-to-max ranges.
RESULTS: Option implants exhibited higher micromotion in dry conditions compared to precoated implants (p = 0.03). Under contamination, both designs demonstrated similar micromotion values. Fixation strength did not significantly differ between designs under dry, uncontaminated conditions (p > 0.99). However, under contaminated conditions, the failure load for the non-coated Option implant was nearly half that of the uncontaminated counterparts (3517 N, 2603-4367 N vs 7531 N, 5163-9000 N; p = 0.002). Precoat implants displayed less susceptibility to fat contamination (p = 0.30).
CONCLUSIONS: NexGen® implant PMMA precoating might reduce the risk of aseptic loosening and revision surgery in case of eventual bone-marrow fat contamination.
方法:研究了两组NexGen®柄胫骨植入物(尺寸为4):Option植入物(N=12)和PMMAPrecoat植入物(N=12)。每个植入物设计分为两个亚组,(N=6),一个亚组在植入物-水泥界面处具有骨髓脂肪,另一个没有污染。在机械试验机中,植入物进行了20,000个周期的单轴加载,同时记录胫骨基板的垂直微动和迁移。随后,推出测试评估水泥界面的固定强度。使用非参数统计比较结果,并表示为中值和最小至最大范围。
结果:与预涂植入物相比,Option植入物在干燥条件下表现出更高的微运动(p=0.03)。在污染之下,两种设计都展示了相似的微动值。在干燥条件下,各设计之间的固定强度没有显著差异,无污染条件(p>0.99)。然而,在受污染的条件下,未涂覆的Option植入物的破坏载荷几乎是未被污染的植入物的一半(3517N,2603-4367Nvs7531N,5163-9000牛顿;p=0.002)。预涂层植入物对脂肪污染的敏感性较低(p=0.30)。
结论:NexGen®种植体PMMA预涂层可降低最终骨髓脂肪污染时无菌性松动和翻修手术的风险。